Identifying and treating lung tissue abnormalities presents challenges that are somewhat unique to the lungs. If a tissue lesion or tumor is to be identified and excised surgically, the chest wall must be opened to provide access to the lungs. Opening the chest wall is a common procedure but one that presents risks of infection and lengthy recovery time, nonetheless. If a tissue lesion or tumor is to be identified endoscopically, the complicated bronchial maze must be navigated.
Bronchoscopes are small cameras attached to the end of a navigable probe and are useful in navigating the airways. The live, illuminated images provide the physician a direct look at the inside surfaces of the airways; however, these bronchoscopes have some inherent shortcomings. First, their present size limits how far into the airways they can be navigated. The airways decrease in diameter as the alveoli are approached. Second, the lungs are a moist environment and can cause the camera lens to become obscured with moisture. Similarly, if a tissue procedure, such as a biopsy, is performed in an airway that can accommodate an endoscope and a cutting tool, there is a chance that blood, mucous, or tissue may land on the lens and obscure the physician's view.
To address the first shortcoming, technology has been developed that allows a physician to track, in real-time, the position of a probe (hereinafter “locatable guide” or “LG”) traveling through the airways. This technology incorporates a plurality of coils at the end of an LG and a magnetic field generator outside of the patient. The patient is placed in the magnetic field created by the generator. As the LG is navigated through the airways, electrical current is induced in the coils and sent via conductors to a computer. The computer can calculate the position and orientation of the probe based on the relative strengths of the current being induced. This technology is shown and described in greater detail in U.S. Pat. Nos. 7,233,820 6,226,543, 6,188,355, 6,380,732, 6,593,884, 6,711,429, 6,558,333, 6,887,236, 6,615,155, 6,574,498, 6,947,788, 6,996,430, 6,702,780, and 6,833,814; and U.S. Patent Publications 20050171508, 20030074011, 20020193686, each of which is incorporated by reference herein in its entirety and also PCT application WO 03/086498 titled ‘Endoscope Structure and Techniques for Navigation in Brunched Structure’ to Gilboa, fully incorporated herein by reference.
These references describe a method and apparatus in which a thin locatable guide, enveloped by a sheath, is used to navigate a bronchoscopic tool to a target location within the lung, aimed in particular to deliver treatments to the lung periphery beyond the bronchoscope's own reach. The coordinates of the target are predetermined based upon three-dimensional CT data. A location sensor is incorporated at the locatable guide's tip. The enveloped guide is inserted into the lung via the working channel of a bronchoscope. First, the bronchoscope's tip is directed to the furthest reachable location in the direction of the target. Next, the guide is advanced beyond the tip of the bronchoscope towards the designated target, based on the combination of the CT data and the position of the guide's tip as measured in body coordinates. When the guide's tip is at the target, the guide is withdrawn, freeing the sheath for insertion of a bronchoscopic tool. In order to prevent the distal end portion of the sheath from sliding away from the target, the sheath is locked to the bronchoscope's body and the bronchoscope itself is held steadily to prevent it from slipping further into the lungs or outwards. Because the airways in the periphery of the lung are narrow, approximately in the same dimensions as the sheath, sideways movements are extremely limited.
The above system and apparatus are aimed to navigate standard bronchoscopic tools to a target located in the lung. In its basic operation, first the target is identified in the CT data, then the guide is navigated to the target and a medical treatment is delivered. It would be advantageous, however, to perform more sophisticated treatments, such as by combining different types of treatments into a single session. Because these locatable guides are smaller than endoscopes, they can travel deeper into the airways. Additionally, rather than relying on visible landmarks and the physician's knowledge of the anatomy of the airways, the position of the LG is superimposed on a computer rendering or x-ray image of the lungs, thereby increasing the navigation value of the sensor. Advantage may be taken of both technologies by placing a probe within a working channel of the endoscope. Thus, real-time images may be viewed while navigating the endoscope as far into the airways as its size allows. Then, the LG is advanced out of the distal end of the working channel of the bronchoscope and deeper into the airways. The LG is surrounded by a sheath. In some embodiments the sheath is steerable and in others, the LG itself is steerable.
Once the LG has been navigated to a target area, presently the LG is retracted through the sheath, while the sheath is left in place. The sheath is referred to as an “extended working channel” (“EWC”) because it is effectively an extension of the working channel of the bronchoscope. The EWC is then used as an avenue for inserting working tools to the target site. Such tools include biopsy needles, ablation devices, etc. After the LG is removed from the EWC, the physician is operating blind, relying on the EWC to remain fixed at the target site. If a tool, such as an aspiration needle or an ablation tool, is being used that requires repositioning in order to treat a greater target area, the repositioning must be done without guidance.
There is a need for an apparatus that allows a physician to operate on a target site endoscopically, while benefiting from the concurrent use of a bronchoscope, an LG, or both. There is a further need for an endoscopic tool that has the capability of maintaining a clear lens during a procedure in a moist environment.